In-tank articles which dispense a disinfecting agent are well known. These articles employ a chemical or combination of chemicals which release a halogen containing disinfecting agent when in contact with water. A build-up of the concentration of the halogen disinfecting agent to saturation by that agent can occur within a few days and this can cause harmful affects to the tank itself and any of the associated flushing elements contained within that tank. In order to control the halogen release rate, which also controls the harmful effects of the halogen in the tank and can prolong the useful life of the product, the chemical system employed is usually contained within some type of a dispensing system such as a container or a metering device. The dispensing system is an inconvenient and messy component of the product which must be removed from the tank and disposed of when the chemicals are exhausted.
Use of a product which can be simply dropped into the tank will eliminate the dispenser but such a product reintroduces all of the problems which the dispenser was designed to circumvent. For instance, the dispenser limited the quantity of water which contacted the chemicals or limited the surface area of the chemicals in contact with the water or limited the release of the halogen containing water into the body of the tank or provided more than one of these functions. Without the container or dispenser, all of the water within the tank can come into contact with the entire surface area of the chemicals.
The formulation of a drop-in product which releases the halogen disinfecting agent over a period of several hours is feasible. However difficulty in formulation increases rapidly as the amount of time over which the product is desired to be active increases. If it is desired to have a controlled, substantially constant rate of halogen disinfectant agent release in a range for instance of 0.5 to 5 ppm, the difficulty increases exponentially as the useful life increases beyond a time of about 1 week. Nevertheless, consumers do not wish to constantly replenish a drop-in lavatory cleaning block and desire a product which needs to be replaced after at least 2 months, and preferably about every 3 to 4 months of use. The fact that toilet systems are essentially static as opposed to dynamic systems where the water is constantly flowing adds additional difficulties.
It is the object of this invention to provide a toilet cleaning block which releases a halogen disinfecting agent in a controlled, substantially constant rate for 2 to 4 months of constant contact with water and at the end of this time has been completely dissolved by the water. This and other objects of the invention will become apparent to those skilled in this art from the following detailed description.